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Problems encountered in Email attachments

Document exchange through email attachments is a very common practice, especially in business field. However, the senders may not be aware that some of their email attachments actually contain sensitive or personal information which should not be revealed to their recipients. This creates a potential problem of confidential data leakage.

On the other hand, even the sender is aware of this it is still inconvenient and time-consuming to make a copy for each sensitive document and to remove those confidential contents in the copy before sending it. Therefore there is a demand for the email clients to handle such documents in a secure way.

Our solutions

We provide a Thunderbird add-on called "Sensitive Attachment Guard" which is able to detect the existence of sensitive information in the email attachments (for Word 2007 and Excel 2007 documents only) and to notify the sender accordingly. Moreover, it provides a function for the sender to strip away the sensitive contents from the attachments which will possibly be delivered to the selected recipients.

Working principles

The figure below illustrates a simple workflow of our add-on. When the user sends the email, the add-on checks the attachments for the existence of sensitive information. If any sensitive contents are detected, it will alert the sender and ask him/her whether to remove such contents before sending.

Another feature of the add-on is the ability for the sender to select which recipients should have the sensitive contents removed in their received attachments. For example, in the figure on the right, the sender sends an email to both recipients A and B with a Word document as attachment. Upon the detection of personal information, such as identity number and account number, the add-on requests the sender to choose which recipients should not receive such data. The sender then selects recipient B and, as a result, recipient B cannot view such data while recipient A can.

System Requirements for Sensitive Attachment Guard

The add-on can be installed to the Thunderbird email client with the followings installed on the system:
  1. Mozilla Thunderbird version 3.x
  2. Sun Java Runtime Environment (JRE) 6 or higher
  3. Microsoft Office 2007



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